1. Field of the Invention
The present invention relates to a two-fluid dispensing system for supplying two fluids from a fuel reservoir and a reductant reservoir to a fuel tank and a reductant tank, respectively. The system ensures that the reductant tank is replenished during fueling of the vehicle.
2. Background of the Invention
Diesel engines are subject to increasingly stringent regulations on the allowable emission levels of nitrogen oxides. One measure to reduce nitrogen oxides (NOx) emitted at the tailpipe is to process exhaust gases discharged from the engine in a lean NOx catalyst.
Lean NOx catalysts are able to process NOx in the presence of a reducing agent. Commonly used reducing agents are fuel, hydrocarbons (other than fuel), and urea, an aqueous solution of ammonia. Liquid hydrocarbons other than fuel, urea, and any other liquid reductant, that might be identified to reduce NOx, are provided from a reservoir. If the diesel engine is mobile, a reductant reservoir is supplied on board the vehicle.
In U.S. Pat. No. 6,216,755 B1, a device for simultaneously filling a fuel tank and a reducing agent tank with a single pump nozzle is disclosed. The inventors of the present invention have recognized a primary problem with ""755 in that the ""755 system contains no provision to prevent the operator of the vehicle from filling the fuel tank using a diesel only dispenser. Thus, although ""755 provides for simultaneous filling of the two tanks, the operator may not avail themselves of that facility due to economic or convenience reasons. If the reductant tank were depleted, a serious degradation in the efficacy of the exhaust aftertreatment device would result; thus, leading to an increase in NOx emissions from the vehicle. The inventors of the present invention have recognized that there is no provision for ensuring that the reductant tank is replenished in the ""755 system.
Disadvantages of prior approaches are overcome by a dispensing system for periodically dispensing a primary fluid from a primary reservoir disposed in a dispenser to a primary tank onboard a vehicle and dispensing a secondary fluid from a secondary reservoir disposed in the dispenser to a secondary tank onboard the vehicle. Both the primary fluid and the secondary fluid are dispensed through a dispensing nozzle coupled to the primary reservoir and the secondary reservoir. The dispensing system includes: a primary dispensing passageway through which the primary fluid flows from the primary reservoir to the dispensing nozzle, a secondary dispensing passageway through which the secondary fluid flows from the secondary reservoir to the dispensing nozzle, a primary valve located in the primary dispensing passageway, a secondary valve located in the secondary dispensing passageway, and a retaining means for retaining the primary valve in a closed position when the secondary valve is in a closed position. The dispensing system provides that the ratio of a dispensing flow rate of the secondary fluid to the dispensing flow rate of the primary fluid is greater than a ratio based on an anticipated consumption rate during engine operation of the secondary fluid relative to the primary fluid.
Also disclosed is a system onboard a vehicle for periodically receiving a primary fluid and a secondary fluid from a dispensing system. The dispensing system includes a primary fluid reservoir, a secondary fluid reservoir, and a dispensing nozzle coupled to the primary fluid reservoir and the secondary fluid reservoir. The system onboard the vehicle includes: a filler neck coupled to the exterior of the vehicle into which a dispensing nozzle is coupled, a primary fluid tank disposed on the vehicle, a primary filling passageway connected to the filler neck at an upstream end of the primary filling passageway and connected to the primary fluid tank at a downstream end of the primary filling passageway, the primary filling passageway conducts primary fluid from the filler neck to the primary fluid tank, a secondary fluid tank disposed on the vehicle, a secondary filling passageway disposed in the filler neck at an upstream end of the secondary filling passageway and connected to the secondary fluid tank, and a preventing means to prevent receiving of the primary fluid until flow of secondary fluid through the secondary filling passageway is initiated.
A method is also disclosed for periodically dispensing a primary fluid from a primary reservoir disposed in a dispensing system to a primary tank onboard a vehicle and periodically dispensing a secondary fluid from a secondary reservoir disposed in a dispensing system to a secondary tank onboard a vehicle. The secondary fluid is dispensed from the secondary fluid reservoir to the secondary fluid tank when a level in the secondary fluid tank is less than a predetermined level; the flow of the primary fluid from the primary fluid reservoir to the primary fluid tank is prevented when a level in the secondary fluid tank is less than a predetermined level.
A primary advantage of the present invention is that, in some conditions, primary fluid may not be dispensed unless the secondary fluid is also dispensed. If the primary fluid is diesel fuel, the operator is motivated to refill the primary tank to propel their vehicle. Secondary fluid (reductant) is dispensed concurrently with fuel or secondary fluid dispensing is initiated prior to dispensing fuel. In either case, a supply of reductant for emission control is ensured.
A further advantage of the present invention is that because two fluids are dispensed into two tanks through one nozzle, the operator is presented with a dispensing system similar to prior experience. That is, secondary fluid may be dispensed without additional action upon the part of the operator. In fact, the operator may not even be aware that a secondary fluid is being dispensed.
Another advantage of the present invention is that because the dispensing flow rate of secondary fluid is such that it is dispensed faster than its anticipated use rate relative to the dispensing flow rate of primary fluid, the secondary fluid tank is filled prior to when the primary fluid tank is replenished thus ensuring that secondary fluid is available on board to supply the exhaust aftertreatment system.
Yet another advantage of the present invention is that shut off of the secondary flow is provided, thereby addressing spillage and fluid intermixing concerns.